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Wireless Charger——"Space Charge" from the STEM Perspective

1. Overview of wireless charging

A wireless charger refers to a charger that does not use a traditional charging power cord to connect to the terminal device that needs to be charged. Therefore, wireless charging is a technology that uses non-physical contact to achieve power transmission. There are currently three common wireless transmission technologies for electric energy, namely electromagnetic induction, electromagnetic resonance, and radio wave. Among them, electromagnetic induction is a widely used method, which not only has high charging efficiency, but also low cost.


2. The history and development trend of wireless charging technology

As early as 1899, physicist Nikola Tesla had already begun the exploration of wireless power transmission. He built a wireless power transmission tower in New York and conceived a wireless power transmission method: using the earth as the inner conductor and the earth’s ionosphere as the outer conductor, amplifying the transmitter in a radial electromagnetic wave oscillation mode to establish between the earth and the ionosphere A low-frequency resonance of about 8 Hz is generated, and then the surface electromagnetic waves surrounding the earth are used to transmit energy. Although this idea was not realized at the time, it was a bold exploration of wireless charging by scientists a hundred years ago.


Nowadays, people continue to research and experiment on this basis, and successfully developed wireless charging technology, and the initial scientific concept is gradually landing. Wireless charging (using electromagnetic induction) is very popular in today's market. In addition to the most widely used mobile and portable fields, it also plays a great role in industrial control and medical fields, and has bright application prospects.


3. Look at wireless chargers from a STEM perspective

S: The working principle of electromagnetic induction wireless charging

Using the principle of electromagnetic induction: Install the transmitter coil on the wireless charging base, and install the receiver coil on the back of the mobile phone. When the mobile phone is charged close to the charging base, the transmitter coil will generate an alternating magnetic field due to AC power. The change of the magnetic field will generate an induced current in the receiving coil, thereby transferring energy from the transmitting end to the receiving end, and finally completing the charging process.


T, E: Work system analysis and design

The wireless charging system is based on the principle of electromagnetic induction, relying on two coupling coils in contact with each other to achieve the transmission of electric energy, and is composed of a wireless power supply system and a wireless receiving system. The wireless power supply system is composed of system modules, power amplifiers and wireless transmitter modules. The wireless receiving system consists of an induction coil receiving module, a charging detection module and an intelligent power-off module. It is composed of two parts: the transmitting end coil and the receiving coil.


M: Testing of wireless charger

In order to improve the safety, performance and electromagnetic compatibility of wireless charger products, it is necessary to carry out specific test items for the product, such as operating frequency test, transmission efficiency test, effective transmission distance test, foreign body detection ability test and temperature test, etc.


Taking the effective transmission distance test as an example, the effective transmission distance is an important quality index for evaluating wireless charging products. The transmission distance directly affects the charging efficiency. After reaching a certain charging efficiency, the longer the transmission distance, the better the transmission performance of the product.


In the future, wireless power supply modules can be implanted anywhere in life and work. At the same time, mobile phones, computers and other electronic devices can also be implanted wireless receiving modules, so that these devices can be easily and quickly charged at any time, then we will say goodbye to data The era of wire, ushered in the era of wireless!